Previous elevated floor plates usually had rectangular rib patterns such as shown in U.S. Pat. No. 3,295,272 of Tomonobu Kanno issued Jan. 3, 1967. Also the depth of the ribs varied, and similar ribs were always of uniform thickness as they extended across the bottom of the plate. These criteria also applied to polygonal tessellation patterns, even including octagons and squares. If ejector pin bosses were incorporated in the grid, they were usually hidden at the junctions of the ribs or at the corners of the polygons in the pattern.